LED lighting controller allows precise dimming

March 08, 2018 //
By Julien Happich

ON Semiconductor has released two QR PSR PWM controllers for LED lighting with Power Factor Control (PFC) function. Both the dimmable NCL30386 and the non-dimmable NCL30388 are high power factor (PF), single stage, constant current (CC) and constant voltage (CV) primary side regulated (PSR) pulse width modulation (PWM) controllers for Flyback, Buck-Boost or Sepic power topologies.

They operate in Quasi-Resonant (QR) mode to achieve efficiency levels that exceed those stipulated in power standards such as the EU’s Ecodesign as well as ENERGY STAR and the NEMA SSL regulations.

The integrated digital power factor correction (PFC) algorithm ensures a market-leading PF of greater than 0.95 and total harmonic distortion (THD) of less than 10% across a universal input voltage range. Integrated high voltage startup current source ensures fast startup, low standby power and wide range operation at the output. Current and voltage are regulated via a digital PSR CC/CV loop control, typically achieving in the region of ±2%, to give highly uniform lighting brightness under all conditions.

The devices are simple to use and operate from a wide VCC range of 9.2-26VDC, with valley lock-out and frequency fold-back ensuring high efficiency across the entire voltage range. Design is further simplified by the inclusion of safety features such as brown-out and overvoltage protection plus the ability to detect short circuits in the output, winding and diode. Neither the NCL30386 nor the NCL30388 require many external components to complete the design, reducing time-to-market, BoM cost and the space required to realise a complete lighting solution.

The NCL30386 offers excellent dimming features, including the option for either linear or quadratic dimming curves. The wide analog dimming range is controlled by two dedicated analog / PWM control pins that allow for precise dimming with a 0.5% minimum dimming ratio - and no audible noise present.